Multifunctional ablation device

ABSTRACT

An intravascular catheter is provided, including a flexible elongate body; an expandable element positioned on the elongate body; a substantially linear thermal segment located proximally of the expandable element, the thermal segment defining a first flexibility, where the thermal segment is positioned between two portions of the catheter body each including a flexibility less than that of the thermal segment; a first fluid flow path in fluid communication with the expandable element; and a second fluid flow path in fluid communication with the thermal segment.

CROSS-REFERENCE TO RELATED APPLICATION

N/A

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

N/A

FIELD OF THE INVENTION

The present invention relates to a method and system for thermal tissuetreatment, and in particular, towards systems and methods of use thereoffor treating multiple tissue sites having varying geometries.

BACKGROUND OF THE INVENTION

Minimally invasive devices, such as catheters, are often employed forsurgical procedure, including those involving ablation, dilation, andthe like. In a particular situation, an ablation procedure may involvecreating a series of inter-connecting lesions in order to electricallyisolate tissue believed to be the source of an arrhythmia. During thecourse of such a procedure, a physician may employ several differentcatheters having variations in the geometry and/or dimensions of theablative element in order to produce the desired ablation pattern. Eachcatheter may have a unique geometry for creating a specific lesionpattern, with the multiple catheters being sequentially removed andreplaced to create the desired multiple lesions. Exchanging thesevarious catheters during a procedure can cause inaccuracies or movementin the placement and location of the distal tip with respect to thetissue to be ablated, and may further add to the time required toperform the desired treatment. These potential inaccuracies and extendedduration of the particular procedure increase the risk to the patientundergoing treatment. Accordingly, it would be desirable to provide asingle medical device having the ability to provide ablative patterns ofvarious shapes, without the need for additional catheters or the likehaving a single geometric orientation, and thus, limited in the abilityto provide multiple ablative patterns.

SUMMARY OF THE INVENTION

The present invention advantageously provides a medical system havingthe ability to provide ablative patterns of various shapes to treatdifferent targeted tissue sites while maintaining a substantially staticposition of the medical device. In particular, a medical device isprovided, having an elongate catheter body; a first treatment region onthe catheter body; a second treatment region proximal to the firsttreatment region, where the second treatment region defines a firstdeflection profile and is disposed between two adjacent catheter bodysegments defining deflection profiles different from the firstdeflection profile, and a third treatment region located distally of thefirst treatment region. The first treatment region may include anexpandable element and the second treatment region can include asubstantially linear thermal segment. The first treatment region may beoperable independently from the second treatment region. The device mayfurther include a first fluid flow path in fluid communication with thefirst treatment region, a second fluid flow path in fluid communicationwith the second treatment region, and a cryogenic fluid source in fluidcommunication with at least one of the first and second fluid flowpaths. Radiopaque markers may be positioned at a boundary between thesecond treatment region and one of the adjacent catheter body segments.

An intravascular catheter is also provided, including a flexibleelongate body; an expandable element positioned on the elongate body; asubstantially linear thermal segment located proximally of theexpandable element, the thermal segment including a flexibility ordeformational capacity, where the thermal segment is positioned betweentwo adjacent portions of the catheter body each including a flexibilityor deformational capacity different from the thermal segment (forexample, the adjacent portions having a rigidity greater than a rigidityof the thermal segment); a first fluid flow path in fluid communicationwith the expandable element; and a second fluid flow path in fluidcommunication with the thermal segment. The first fluid flow path may beoperable independently from the second fluid flow path. The first fluidflow path may include a first fluid injection lumen, the second fluidflow path may include a second fluid injection lumen; and the firstfluid flow path and the second fluid flow path can include a commonexhaust lumen.

A method of treating cardiac tissue is also provided, includingpositioning an expandable element of a medical device proximate apulmonary vein; positioning a substantially linear thermal segment ofthe medical device proximate an atrial wall, the thermal segment beingmore flexible than medical device segments adjacent to the thermalsegment; applying a deflective force from a proximal portion of themedical device to the thermal segment, the deflective force causing thethermal segment to deflect towards the atrial wall; and ablating atleast one of the pulmonary vein and the atrial wall with the medicaldevice. Positioning the expandable element can include expanding theexpandable element in the pulmonary vein to substantially occlude thepulmonary vein; applying a deflective force can include applying anaxial force in a distal direction along a longitudinal axis of themedical device; and ablating at least one of the pulmonary vein and theatrial wall can include circulating a cryogenic fluid through at leastone of the expandable element and the thermal segment.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings wherein:

FIG. 1 is an illustration of an embodiment of a medical systemconstructed in accordance with the principles of the present invention;

FIG. 2 is an illustration of an embodiment of a medical deviceconstructed in accordance with the principles of the present invention;

FIG. 3 is an additional illustration of the medical device shown in FIG.2; and

FIG. 4 is an illustration of an exemplary use of a medical deviceconstructed in accordance with the principles of the present invention;and

FIG. 4 is an additional illustration of an exemplary use of a medicaldevice constructed in accordance with the principles of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention advantageously provides a medical system havingthe ability to provide ablative patterns of various shapes to treatdifferent targeted tissue sites while maintaining a substantially staticposition of the medical device. Referring now to the drawing figures inwhich like reference designations refer to like elements, an embodimentof a medical system constructed in accordance with principles of thepresent invention is shown in FIG. 1 and generally designated as “10.”The system generally includes a cooling unit or console 12 coupled to amedical device 14 through an umbilical system 16. The medical device 14may be a medical probe, a catheter, a balloon-catheter, as well as otherdevices deliverable or otherwise positionable through the vasculatureand/or proximate to a tissue region for treatment. In particular, themedical device 14 may include a device operable to thermally treat aselected tissue site, including cardiac tissue. The medical system 10may also include one or more sensors to monitor the operating parametersthroughout the system, including for example, pressure, temperature,flow rates, volume, or the like in the console 12, the umbilical system16, and/or the medical device 14.

Umbilical system 16 may include three separate umbilicals: a coaxialcable umbilical 18, an electrical umbilical 20 and a vacuum umbilical22. Although separate umbilicals are shown, it is contemplated that oneor more connections may be included in one or more umbilicals having oneor more coaxial or otherwise integrally contained passages or conduitstherethrough providing electrical and fluid communication between themedical device 14 and the console 12. An outer vacuum umbilical may besuitable for a medical device having multiple layers or balloons. If theuser wishes to perform a radiofrequency (“RF”) ablation procedure,radiofrequency energy can be provided to electrodes on the medicaldevice 14 via electrical umbilical 20 to perform an RF ablationtechnique. Electrical umbilical 20 can include an electrocardiograph(“ECG”) box 24 to facilitate a connection from one or more electrodes onthe medical device 14 to an ECG monitor (not shown). Coaxial umbilical18 may include both a cooling injection umbilical and a vacuum umbilicalthat provide respective inlet and return paths for a refrigerant orcoolant used to cool a tissue-treating section of the device 14. Thevacuum umbilical 22 may provide a safety conduit allowing excess coolantor gas to escape from the device 14 if the pressure within the medicaldevice 14 exceeds a predefined limit. The vacuum umbilical 22 can alsobe used to capture air through a leak of the outer vacuum system whereit is outside the patient and as a lumen to ingress blood when insidethe patient.

Now referring to FIG. 2, the medical device 14 is shown in more detail.The medical device 10 may include an elongate body 26 passable through apatient's vasculature. The elongate body 26 may define a proximalportion and a distal portion, and may further include one or more lumensmay disposed within the elongate body 26 thereby providing mechanical,electrical, and/or fluid communication between the proximal portion ofthe elongate body 26 and the distal portion of the elongate body 26. Forexample, the elongate body 26 may include an injection lumen 28 and anexhaust lumen 30 defining a fluid flow path therethrough. In addition,the elongate body 26 may include a guidewire lumen 32 movably disposedwithin and/or extending along at least a portion of the length of theelongate body 26 for over-the-wire applications. The guidewire lumen 32may define a proximal end and a distal end, and the guidewire lumen 32may be movably disposed within the elongate body 26 such that the distalend of the guidewire lumen 32 extends beyond and out of the distalportion of the elongate body 26.

The medical device may include one or more treatment regions forenergetic or other therapeutic interaction between the medical device 14and a treatment site. The treatment regions may deliver, for example,radiofrequency energy, cryogenic therapy, or the like. For example, thedevice 14 may include a first treatment region 34 having a thermaltreatment element, such as an expandable membrane or balloon and/or oneor more electrodes or other thermally-transmissive components, at leastpartially disposed on the elongate catheter body. In a particularexample, the first treatment region 34 may include a firstexpandable/inflatable element or balloon 36 defining a proximal endcoupled to the distal portion of the elongate body 26 of the medicaldevice 14, while further defining a distal end coupled to the distal endof the guidewire lumen 32. As such, due to the movable nature of theguidewire lumen 32 about the elongate body 26, any axial and/orlongitudinal movement of the guidewire lumen 32 may act to tension orloosen the first expandable element 36, i.e., extend or retract theexpandable element 36 from a lengthened state to a shortened stateduring an inflation or deflation thereof. In addition, the firstexpandable element 36 may have any of a myriad of shapes, and mayfurther include one or more material layers providing for punctureresistance, radiopacity, or the like. The first expandable element 36may be in communication with the fluid injection and exhaust lumens ofthe medical device 14 as described above.

The medical device 14 may further include a second expandable/inflatableelement or balloon 38 contained within or otherwise encompassed by thefirst expandable element 36 such that an interstitial region, envelopeor space 40 is defined therebetween. The second expandable element 38may be in communication with the fluid injection and exhaust lumens ofthe medical device 14 as described above, i.e., a fluid flow path mayprovide an inflation fluid or coolant, such as a cryogenic fluid or thelike, to the interior of the second expandable element 38. Further, theinterstitial region 40 may be in fluid communication with aninterstitial lumen 42 providing a fluid flow path or avenue separate andindependent from a fluid flow path delivering fluid or otherwise incommunication with an interior of the second expandable element 38. Thesecond pathway provides an alternate exhaust route for fluid that mayleak from the interior of the second expandable element 38 into theinterstitial region 40 or fluid entering the medical device 14 from theexterior. In particular, the isolation of the interstitial lumen 42 fromthe interior of the second expandable element 38 provides an alternateroute for fluid to circulate in the case of a rupture or leak of eitherthe first or second expandable elements, as well as allowing for theinjection or circulation of fluids within the interstitial region 40independently of fluids directed towards the second expandable element38. Towards that end, the interstitial region may be in fluidcommunication with a fluid source, a vacuum source, or the like separatefrom a fluid source, vacuum source or otherwise in fluid communicationwith the interior of the second expandable element 38. Alternatively,the interstitial lumen 42 may be joined to or otherwise in fluidcommunication with the injection lumen 28 and the interior of the secondexpandable element 38 to provide a single exhaust or vacuum source forthe medical device 14.

Now referring to 3, the medical device may further include a secondtreatment region 44 located proximally of the first treatment region 34,where the second treatment region 44 is operable independently andseparately from the first treatment region 34. For example, the secondtreatment region 44 may be fluidically isolated or sealed from fluidflow with the first treatment region 34. The first and second treatmentregions 34, 44 may generally provide the ability to deliver therapeutictreatment to a plurality of locations while maintaining the medicaldevice 14 in a substantially fixed or static position.

The two treatment regions may also provide the ability to providetreatment or therapeutic energy to varying locations having differentdimensions, shapes, or other geometric and anatomical characteristics.As described above, the first treatment region 34 may include one ormore expandable elements or balloons. The first treatment region 34 maythus provide for arcuate, circular, and/or circumferential treatmentpatterns. In turn, the second treatment region 44 may include asubstantially linear, elongate thermal segment 46 enabling energetic orthermal exchange with a contacted tissue area. Of note, the thermalsegment 46 may be substantially linear when not experiencing anyexternal loading or force, but may retain sufficient flexibility tocurve into an arcuate, curvilinear shape to contact a desired tissueregion. The thermal segment may be constructed from one or morematerials imparting thermally conductive properties, such as nylon,polyethylene terephthalate (“PET”), and/or polyethylene (“PE”) forexample. In particular, the thermal segment 46 may provide sufficientthermal conductivity for ablation of contacted tissue through the use ofa cryogenic refrigerant or a radiofrequency or other heat source coupledto or otherwise in thermal communication with the thermal segment 46.

Such thermal communication may be achieved, for example, by a fluid flowpath in fluid communication with the thermal segment 46 that isindependently operated or otherwise separated from a fluid flow pathdelivering a cooling or treatment medium to the first treatment region34. For example, a secondary fluid injection lumen 48 may be in fluidcommunication with an interior of the thermal segment 46 of the secondtreatment region 44. The secondary fluid injection lumen 48 may includeone or more apertures 50 therein for dispersing, expanding, or otherwisedelivering a fluid to the thermal segment 46. The secondary fluidinjection lumen 48 may be placed in fluid communication with a fluidsupply common to the first treatment region 34, or may be coupled to aseparate and independently operated fluid source. Where a common fluidsource is elected, one or more valves, controllers, or the like mayprovide for the controlled, independent, and separate dispersion orcirculation of fluid through the two injection lumens. Such valves,controllers, or the like may be located in a portion of the medicaldevice 14 and/or in the console 12.

The thermal segment 46 may further include sealed transverse sections orwalls 52, 52′ spanning from the outer walls or layers of the elongatebody 26 and around the one or more lumens extending towards the distalportion of the medical device that restrict or wholly prevent fluiddispersed within the thermal segment 46 from travelling distally towardsthe first treatment region 34. The thermal segment 46 may furtherinclude a secondary exhaust lumen (not shown), or the exhaust lumen 30may be in fluid communication with the second treatment region 44,thereby allowing a single exhaust or vacuum source to remove expendedcoolant from both the first and second treatment regions jointly.

Continuing to refer to FIG. 3, the medical device may further include athird treatment region 53 located distally of the first treatment region34, where the third treatment region 53 is operable independently andseparately from the first and second treatment regions 34, 44 throughone or more independently operated and/or isolated fluid lumens (notshown). For example, the third treatment region 53 may be fluidicallyisolated or sealed from fluid flow with the first and second treatmentregion. The plurality of treatment regions 34, 44, 53 may generallyprovide the ability to deliver therapeutic treatment to a plurality oflocations while maintaining the medical device 14 in a substantiallyfixed or static position. In particular, the third treatment region 53may provide for a “spot” ablation of discrete tissue locations, whilealso providing for anchoring of the distal end of the medical device 14through cryoadhesion with contacted tissue. The third treatment region53 may be constructed from one or more metals, thermally conductivepolymers, and/or composites thereof.

The medical device 14 may further include one or more temperature and/orpressure sensors (not shown) proximate the treatment region(s) formonitoring, recording or otherwise conveying measurements of conditionswithin the medical device 14 or the ambient environment at the distalportion of the medical device 14. The sensor(s) may be in communicationwith the console 12 for initiating or triggering one or more alerts ortherapeutic delivery modifications during operation of the medicaldevice 14.

Referring to FIGS. 2 and 3, the medical device 14 may include a handle54 coupled to the proximal portion of the elongate body 26, where thehandle 54 may include an element such as a lever or knob 56 formanipulating the catheter body and/or additional components of themedical device 14. For example, a pull wire 58 with a proximal end and adistal end may have its distal end anchored to the elongate body 26 ator near the distal end. The proximal end of the pull wire 58 may beanchored to an element such as a cam in communication with andresponsive to the lever 56.

The handle 54 can further include circuitry for identification and/oruse in controlling of the medical device 14 or another component of thesystem. For example, the handle may include one or more pressure sensors60 to monitor the fluid pressure within the medical device 14.Additionally, the handle may be provided with a fitting 62 for receivinga guidewire that may be passed into the guidewire lumen 32.

The handle 54 may also include connectors that are matable directly to afluid supply/exhaust and control unit or indirectly by way of one ormore umbilicals. For example, the handle may be provided with a firstconnector 64 that is matable with the co-axial fluid umbilical 18 and asecond connector 66 that is matable with the electrical umbilical 20.The handle 54 may further include blood detection circuitry 68 in fluidand/or optical communication with the injection, exhaust and/orinterstitial lumens. The handle 54 may also include a pressure reliefvalve 70 in fluid communication with the injection, exhaust and/orinterstitial lumens to automatically open under a predeterminedthreshold value in the event that value is exceeded.

Continuing to refer to FIGS. 2-3, the medical device 14 may include anactuator element 72 that is movably coupled to the proximal portion ofthe elongate body 26 and/or the handle 54. The actuator element 72 mayfurther be coupled to the proximal portion of the guidewire lumen 32such that manipulating the actuator element 72 in a longitudinaldirection causes the guidewire lumen 32 to slide towards either of theproximal or distal portions of the elongate body 26. As a portion ofeither and/or both the first and second expandable elements 36,38 may becoupled to the guidewire lumen 32, manipulation of the actuator element72 may further cause the expandable element(s) to be tensioned orloosened, depending on the direction of movement of the actuator element72, and thus, the guidewire lumen 32. Accordingly, the actuator element72 may be used to provide tension on the expandable element(s) 36,38during a particular duration of use of the medical device 14, such asduring a deflation sequence, for example. The actuator element 72 mayinclude a thumb-slide, a push-button, a rotating lever, or othermechanical structure for providing a movable coupling to the elongatebody 26, the handle 54, and/or the guidewire lumen 32. Moreover, theactuator element 72 may be movably coupled to the handle 54 such thatthe actuator element 72 is movable into individual, distinct positions,and is able to be releasably secured in any one of the distinctpositions.

Referring again to FIG. 3, the second treatment region 44 may bedeflectable, steerable, or otherwise manipulated into a desired positionor configuration independently or differently from the first treatmentregion 34 and/or adjacent portions of the elongate body 26. Inparticular, the elongate body 26 of the medical device 14 may beconstructed from one or more layers 74, 74′ of material or differingcomponents to provide a desired degree of flexibility while maintainingthe capability to transmit torque along the length of the medical device14. The layers 74, 74′ may include a multitude of polymers, plastics,and composites thereof, as well as braided or other structuralreinforcing materials/components running therethrough. The elongate body26 may further include one or more steering wires 76 or actuationmechanisms to deliver a force to a particular segment or portion of themedical device 14, such as a region proximate to the second treatmentregion 44, in addition to the pull wire 58 described above, which mayprovide deflection or steering of the first treatment region 34. Theconstruction of the elongate body 26 substantially dictates itsresulting deflection or bending behavior when a force is applied, i.e.,its deflection profile.

The second treatment region 44 may define a deflection profile differentfrom a deflection profile or behavior of adjacent sections 78, 78′ ofthe catheter body 26. For example, the thermal segment 46 of the secondtreatment region 44 may have a construction different from the adjacentsections 78, 78′ of the catheter body 26, resulting in a differentflexibility, deflection or bending result when a force is applied. Thedifferent construction may include different use or multitudes of selectmaterials, as well as using selected materials in a different order orrelationship to one another. In a particular example, the secondtreatment region 44 may have greater flexibility than the adjacentsection 78, 78′. The thermal segment 46 may have a width or thickness ofmaterial less than a width of material constituting portions of thecatheter body 26. In addition and/or as an alternative, the thermalsegment 46 may be devoid of or have reduced structural reinforcingcomponents (such as braided constructs, longitudinal splines, deflectionbiasing members, or the like) compared to portions of the catheter body26. The variations in deflection behavior between the second treatmentregion 44 and the surrounding portions of the catheter body 26 may allowthe second treatment region 44 to be deflected or bent towards atargeted tissue for treatment while the medical device 14 remainssubstantially static or in place. In addition, the variations in bendingor deflection behavior between the second treatment region 44 and thesurrounding catheter body segments may allow for the transmission of adeflective force from a catheter body section to the second treatmentregion 44, as described in more detail below. In addition, one or moreradiopaque markers 79, 79′ may be positioned at a boundary between thesecond treatment region 44 and either of the adjacent catheter bodysections or segments 78, 78′ to facilitate positioning of the treatmentregion through known medical imaging methodologies.

In an exemplary system, a fluid supply 80 including a coolant, cryogenicrefrigerant, or the like, an exhaust or scavenging system (not shown)for recovering or venting expended fluid for re-use or disposal, as wellas various control mechanisms for the medical system may be housed inthe console 12. In addition to providing an exhaust function for thecatheter fluid supply, the console 12 may also include pumps, valves,controllers or the like to recover and/or re-circulate fluid deliveredto the handle 54, the elongate body 26, and treatment region(s) 34,44 ofthe medical device 14. A vacuum pump in the console 12 may create alow-pressure environment in one or more conduits within the medicaldevice 14 so that fluid is drawn into the conduit(s) of the elongatebody 26, away from the treatment region(s) 34, 44, and towards theproximal end of the elongate body 26. The console 12 may include one ormore controllers, processors, and/or software modules containinginstructions or algorithms to provide for the automated operation andperformance of the features, sequences, or procedures described herein.

Now referring to FIGS. 4-5, in an exemplary method of use, the medicalsystem 10 may be used to deliver therapeutic treatment to a plurality oftargeted tissue areas. For example, the medical device 14 may bepositioned and operated to ablate targeted tissue region in the heart.The first treatment region 34 may be positioned in the proximity of apulmonary vein opening or junction 82 with a portion of the atrial wall84. Where the first treatment region 34 includes an expandable element,the expandable element may be inflated or otherwise expanded tosubstantially occlude the pulmonary vein. The occlusion reduces theblood flow around the treatment region 34, thereby allowing enhancedthermal exchange between the medical device 14 and the targeted tissue.The occlusion may further anchor a distal portion of the medical device14, thereby facilitating additional maneuvering, deflection, or the likeof proximal portions of the catheter body 26.

In particular, once the first treatment region 34 has been positionedwhere desired, the second treatment region 44 may subsequently bepositioned proximate targeted tissue for treatment elsewhere in theheart, such as the right atrial isthmus. The general placement andpositioning of the second treatment region 44 may be facilitated by theimaging and tracking of the markers 79, 79′ located at the boundaries ofthe second treatment region 44. Further to the general placement of thesecond treatment region 44, the second treatment region may then besteered or otherwise deflected towards the specific tissue to betreated. The deflection may be achieved by applying a deflection forceat the proximal end of the catheter body 26, through the handle 54 forexample. The force may be a compressive, linear force transmitted alonga longitudinal axis of the catheter body 26. Given the anchoring of thefirst treatment region 34, and the increased rigidity of the catheterbody segments 78, 78′ adjacent the second treatment region 44, thesecond treatment region 44 may deflect outwards or “buckle” as a resultof the linearly/longitudinally applied deflection force (as shown inFIG. 5). This deflection or “buckling” may thus cause increased contactand pressure between the second treatment region 44 and the targetedtissue, thereby providing enhanced or otherwise increased thermalexchange for tissue treatment.

Once the first and second treatment regions have be appropriatelypositioned as described above, the first and second treatment regions34, 44 may be operated to affect a desired therapy, such as tissueablation. The tissue ablation may be achieved by the circulation of acryogenic fluid through either and/or both of the first and secondtreatment regions sequentially and/or simultaneously, for example.

It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed herein above. In addition, unless mention was made above tothe contrary, it should be noted that all of the accompanying drawingsare not to scale. A variety of modifications and variations are possiblein light of the above teachings without departing from the scope andspirit of the invention, which is limited only by the following claims.

1. A medical device, comprising: an elongate catheter body; a first treatment region on the catheter body; a second treatment region proximal to the first treatment region, wherein the second treatment region defines a first deflection profile and is disposed between two adjacent catheter body segments defining deflection profiles different from the first deflection profile.
 2. The medical device of claim 1, wherein the first treatment region includes an expandable element.
 3. The medical device of claim 2, wherein the second treatment region includes a substantially linear thermal segment.
 4. The medical device of claim 1, wherein the second treatment region is more flexible than the adjacent catheter body segments.
 5. The medical device of claim 1, further comprising a third treatment region located distally of the first treatment region.
 6. The medical device of claim 1, wherein the first treatment region is operable independently from the second treatment region.
 7. The medical device of claim 6, further comprising a first fluid flow path in fluid communication with the first treatment region, and a second fluid flow path in fluid communication with the second treatment region.
 8. The medical device of claim 7, further comprising a cryogenic fluid source in fluid communication with at least one of the first and second fluid flow paths.
 9. The medical device of claim 1, further comprising a radiopaque marker positioned at a boundary between the second treatment region and one of the adjacent catheter body segments.
 10. An intravascular catheter, comprising: a flexible elongate body; an expandable element positioned on the elongate body; a substantially linear thermal segment located proximally of the expandable element, wherein the thermal segment is positioned between two adjacent portions of the catheter body, the adjacent portions having a rigidity greater than a rigidity of the thermal segment; a first fluid flow path in fluid communication with the expandable element; and a second fluid flow path in fluid communication with the thermal segment.
 11. The intravascular catheter of claim 10, wherein the first fluid flow path is operable independently from the second fluid flow path.
 12. The intravascular catheter of claim 10, wherein the first fluid flow path includes a first fluid injection lumen, and the second fluid flow path includes a second fluid injection lumen.
 13. The intravascular catheter of claim 12, wherein the first fluid flow path and the second fluid flow path include a common exhaust lumen.
 14. The intravascular catheter of claim 10, further comprising a cryogenic fluid source in fluid communication with at least one of the first and second fluid flow paths.
 15. The intravascular catheter of claim 10, further comprising a radiopaque marker positioned at a boundary between the second treatment region and one of the adjacent catheter body segments.
 16. A method of treating cardiac tissue, comprising: positioning an expandable element of a medical device proximate a pulmonary vein; positioning a substantially linear thermal segment of the medical device proximate an atrial wall, the thermal segment being more flexible than medical device segments adjacent to the thermal segment; applying a compressive force from a proximal portion of the medical device to the thermal segment, the compressive force causing the thermal segment to deflect towards the atrial wall; and ablating at least one of the pulmonary vein and the atrial wall with the medical device.
 17. The method of claim 16, wherein positioning the expandable element includes expanding the expandable element in the pulmonary vein to substantially occlude the pulmonary vein.
 18. The method of claim 16, wherein applying a compressive force includes applying an axial force in a distal direction along a longitudinal axis of the medical device.
 19. The method of claim 16, wherein ablating at least one of the pulmonary vein and the atrial wall includes circulating a cryogenic fluid through at least one of the expandable element and the thermal segment. 